<template>
  <div class="star" :class="' star-' + size ">
    <span class="star-item" v-for="(sc,index) in startClasses" :class="sc" :key="index"></span>
  </div>
</template>

<script>
// 类名常量
const CLASS_ON = 'on'
const CLASS_HALF = 'half'
const CLASS_OFF = 'off'
export default {
    props:{
        score:Number,
        size:Number
    },
    computed:{
      // 一共五星 小数部分大于0.5出现半星
      startClasses(){
        const {score} = this  
        const scs = []
        // 向scs中添加n个CLASS_ON scoreInteger为整数的意思 Math.floor()函数是向下取整
        const scoreInteger = Math.floor(score)
        for (let i = 0; i < scoreInteger; i++){
             scs.push(CLASS_ON)
        }
        // 向scs中添加0/1个CLASS_HALF 由于小数可能会不精准 我们在这里采用乘10
        if (score*10 - scoreInteger*10 > 5){
              scs.push(CLASS_HALF)
        }
        // 向scs中添加n个CLASS_OFF
          while(scs.length < 5) {
              scs.push(CLASS_OFF)
          }
        return scs
    }
  }
};
</script>

<style lang="stylus" scoped>
@import '../../common/stylus/mixins.styl';
.star { // 2x图 3x图
  float: left;
  font-size: 0;

  .star-item {
    display: inline-block;
    background-repeat: no-repeat;
  }

  &.star-48 {
    .star-item {
      width: 20px;
      height: 20px;
      margin-right: 22px;
      background-size: 20px 20px;

      &:last-child {
        margin-right: 0;
      }

      &.on {
        bg-image('./images/star48_on');
      }

      &.half {
        bg-image('./images/star48_half');
      }

      &.off {
        bg-image('./images/star48_off');
      }
    }
  }

  &.star-36 {
    .star-item {
      width: 15px;
      height: 15px;
      margin-right: 6px;
      background-size: 15px 15px;

      &:last-child {
        margin-right: 0;
      }

      &.on {
        bg-image('./images/star36_on');
      }

      &.half {
        bg-image('./images/star36_half');
      }

      &.off {
        bg-image('./images/star36_off');
      }
    }
  }

  &.star-24 {
    .star-item {
      width: 10px;
      height: 10px;
      margin-right: 3px;
      background-size: 10px 10px;

      &:last-child {
        margin-right: 0;
      }

      &.on {
        bg-image('./images/star24_on');
      }

      &.half {
        bg-image('./images/star24_half');
      }

      &.off {
        bg-image('./images/star24_off');
      }
    }
  }
}
</style>